Company: QTIWW
Filing Date: 2025-12-29
Form Type: S-1/A
Source: 0001628280-25-058960
Chunk: 0

Company: QT IMAGING HOLDINGS, INC.
Filing Date: 2025-12-29
Form: S-1/A
Chunk 0
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<div align='center'>As filed with the U.S. Securities and Exchange Commission on December 29, 2025.</div>

#### Registration No. 333-291237

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### AMENDMENT NO. 1 TO

#### FORM S-1

### REGISTRATION STATEMENT

#### UNDER

#### THE SECURITIES ACT OF 1933

#### QT Imaging Holdings, Inc.
<div align='center'>(Exact Name of Registrant as Specified in its Charter)</div>

| Delaware                        |     |                         6770 |     | 85-1728920         |
| (State or Other Jurisdiction of 
 Incorporation or Organization)  |     | -Primary Standard Industrial 
      Classification Code No. |     | -I.R.S. Employer   
 Identification No. |

#### Dr. Raluca Dinu

#### Chief Executive Officer

#### 3 Hamilton Landing, Suite 160,

#### Novato, CA 94949

#### Telephone: (650) 276-7040
<div align='center'>(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)</div>

<div align='center'>Copies to:</div>

#### Jeffrey C. Selman

#### Elena Nrtina

#### DLA Piper LLP (US)

#### 555 Mission Street, Suite 2400

#### San Francisco, California 94105

#### Tel: (415) 615-6035
Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, please check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If